... China API Casing Tube-----------------------------------------------------------------------------------------------------------------Features Materials: H-40,J-55,K-55,N-80,C-75,L ... finish: Plain, BTC, LTC,STC Grades: H-40, J-55, K-55, N-80, C-75, L ... Metal Manufacturing Co., Ltd. in April 2011. (Formerly known as YingKou OuYang Steel Tube Co., Ltd.)YingKou OuYang Metal Manufacturing Co., Ltd. is ...